Positive affect and learning: exploring the “Eureka Effect” in dogs

Abstract

Animals may experience positive affective states in response to their own achievements. We investigated emotional responses to problem-solving in dogs, separating these from reactions to rewards per se using a yoked control design. We also questioned whether the intensity of reaction would vary with reward type. We examined the response (behavior and heart rate) of dogs as they learned to gain access to different rewards: (1) food (2) human contact, and (3) dog contact. Twelve beagles were assigned to matched pairs, and each dog served as both an experimental and a control animal during different stages of the experiment. We trained all dogs to perform distinct operant tasks and exposed them to additional devices to which they were not trained. Later, dogs were tested in a new context. When acting as an experimental dog, access to the reward was granted immediately upon completion of trained operant tasks. When acting as a control, access to the reward was independent of the dog's actions and was instead granted after a delay equal to their matched partner's latency to complete their task. Thus, differences between the two situations could be attributed to experimental dogs having the opportunity to learn to control access to the reward. Experimental dogs showed signs of excitement (e.g., increased tail wagging and activity) in response to their achievements, whereas controls showed signs of frustration (e.g., chewing of the operant device) in response to the unpredictability of the situation. The intensity of emotional response in experimental dogs was influenced by the reward type, i.e., greatest response to food and least to another dog. Our results suggest that dogs react emotionally to problem-solving opportunities and that tail wagging may be a useful indicator of positive affective states in dogs.

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“…Taken together these results indicated that receiving food treats might not be sufficient per se to induce a long-term change in adult pet dogs' autonomic system and this could be due to a number of reasons: on one hand, differently from the two previous studies using food as a reward [43,47], we tested adult pet dogs living within the household and accustomed to receive palatable treats from the owner; this might have limited the positive valence of the food stimulus. On the other hand, in our study food was provided directly to the dogs, i.e.…”

“…HRV could increase [63] or decrease [47] and therefore at the present stage of knowledge on dog emotional reaction is difficult to make a more precise hypotheses. Finally, if receiving treats induced in dogs a positive emotional state we should observe an increase in tail wagging [43].…”

“…While the literature on positive emotions in farm animals has grown [5,27,[33][34][35][36][37][38][39][40][41], the same topic has received little attention in companion animals [42][43][44][45][46][47]. Dogs' positive affective states have been investigated in female laboratory beagles tested in four different experimental protocols:…”

“…tail wagging, proximity and contact seeking, gazing, stress signals, and vocalizations [42][43][44][45][46][47]), physiological (HR and HRV [44,47]), endocrine (oxytocin and cortisol [45]), and neural (hemodynamic [46]) indicators.…”

“…During Phase 2 (Feeding), most of the time dogs remained oriented towards their owner's hands, looking at the food and showing an increased duration of tail wagging. McGowan and colleagues [43] showed that dogs facing a problem-solving task under their control had a more intense emotional response, expressed as frequency of tail wags, when the reward was food rather than contact with a conspecific and suggested that tail wagging can be used as an indicator of a positive affective state in dogs. Quaranta and colleagues [76] showed that dogs wagged their tail in an asymmetric manner in response to different emotional stimuli and that the amplitudes of tail wagging also depend on the stimuli, being highest when seeing the owner and lowest when seeing a cat.…”